Well tool clutch system



United States Patent US. Cl. 166-237 3 Claims ABSTRACT OF THE DISCLOSUREThe particular embodiment disclosed herein as illustrative of one formof the invention is a selectively operable coupling device forcontrolling relative movement between telescoping members in a well toolincluding a segmental nut member between said members and arranged forlateral movement, means for securing said nut member against rotationrelative to one of said members, spaced upper and lower thread portionson said nut member having opposite lead threads, and spaced upper andlower companion threads on the other of said members respectivelyengageable with threaded portions on said nut member to prevent relativemovement, and releasable therefrom to permit relative movement inresponse to rotation of one of said members relative to the other in onerotational direction.

The present invention relates generally to well tools, and morespecifically to a selectively manipulatable device for controllingrelative movement between parts of a well tool.

Many well tools have expansible elements such as slips and packing whichare expanded in a well conduit in response to manipulation of arunning-in string of tubing or drill pipe extending from the tool to theearths surface. Since the tool must first be moved through the wellconduit to a predetermined depth of setting, it is desirable to preventany premature expansion or operation of parts during lowering. Thisnecessitates the use of a control device which can lock the tool partsagainst relative movement during lowering and which can be manipulatedat setting depth from locked to released condition. Moreover, once thetool is set, it may be desirable to lock the various parts in setcondition so that the tool will remain set in the well conduit until itis desired to remove it. Accordingly, the control mechanism should havethe further capability of again locking the various parts againstrelative movement in set positions. Then at some later time it may bedesirable to remove the tool of the well conduit, whereupon the controlmechanism should be manipulatable to a released condition to permitrelative movement to occur in retracting the slips and packing. Finally,it is usually desirable to again lock the various parts in their initialretracted relative position for longitudinal movement in the wellconduit.

The motions which normally can be applied to the running-in string atthe earths surface to operate such a control device are rotationalmotion in either direction and/ or vertical motion, either upward ordownward. One control device which is responsive to these manipulationsand has the above-mentioned capabilities is the so-called clutch nut ordizzy nut system which comprises an expansible and contractable nutmember having threads which are cooperable with mating threads on amandrel to prevent relative movement when engaged, and which arereleasable by relative rotation to permit longitudinal relativemovement. Then the threads can be reengaged by vertical movement withoutrotation due to the one-way ratcheting characteristics of the device.

In the prior art, several diiferent structural arrangements have beenused. For example, US. Patent No. 3,279,542 issued to Brown showsseparate upper and lower clutch nuts which are alternatively engageablewith spaced mandrel threads. This system may function quite effectively,but has the disadvantage that its use necessitates a rather lengthy slipcage, with consequent increase in manufacturing costs and loss of toolcompactness. Another clutch nut arrangement is used in the well toolillustrated in the Oilfield Composite Catalog, l96667, on page 552,wherein a single clutch nut has alternate segments with reverse leadthreads which are respectively alternatively engageable with spacedmandrel threads. This system has the disadvantage that the threads arein engagement only around one-half the thread circumference, resultingin poor load distribution and structural weakness. Still another clutchnut arrangement is shown in US. Patent No. 2,893,492 issued to Brownwherein each clutch nut segment has reverse lead threads which arealternatively engageable with spaced reverse lead mandrel threads. Thisnut configuration is quite diflicult to machine and the thread forms arestructurally weak, particularly at points where the thread formsintersect each other.

The present invention is directed to a new and improved clutch nutarrangement which is cooperable with spaced, reverse lead threadsections on a mandrel to enable selective locking of the mandrel invarious longitudinal positions relative to an outer tubular member, aswell as selective release from locked condition for longitudinalmovement between locked positions. Only a single clutch nut assembly isused so that the system is compact to reduce manufacturing costs. Thenut assembly has longitudinally spaced threads to enable full circleengagement with respective mandrel threads. Thus, loads are evenlydistributed between threads to enhance the strength and load bearingcharacteristics of the system. The respective thread sections are notcoextensive, so that the nut assembly is easily manufactured.

The present invention may be summarized from a conceptual standpoint asa releasable coupling device for use in a well tool to control relativemovement between tubular telescoping members. The coupling deviceincludes radially movable, inwardly biased means between said membershaving longitudinally spaced threaded portions which are respectivelyengageable with spaced threaded portions on one of said members. Meansare provided for preventing relative rotation between said means and theother of said members. The respective threaded portions are constructedand arranged to be engaged with one another in response to longitudinalrelative movement without rotation, and to be disengaged only inresponse to relative rotation, preferably in response to rotation in thesame hand direction.

The present invention has other concepts and advantages which willbecome more clearly apparent in connection with the following detaileddescription. A preferred embodiment is shown in the accompanyingdrawings, in which:

FIGURE 1 is a somewhat schematic cross-sectional view, with portions inside elevation, of a well tool which embodies the principles of thepresent invention;

FIGURE 2 is an enlarged fragmentary cross-section view of the presentinvention to show further structural details thereof; and

FIGURE 3, is a sectional view of the clutch nut assembly of FIGURE 2.

Referring initially to FIGURE 1, the present invention is illustrated inconnection with a well tool 10 for use in a well bore. The well tool 10,although shown in a bridge plug form, can be any type of well devicewhere it is desirable to lock an inner tubular member, such as a centralbody or mandrel, in more than one longitudinal position relative to anouter tubular member, such as a slip cage. One of the relative positionsmay correspond to the running-in condition of the tool where slips andpacking are retracted. In the other relative positions, the slips andthe packing may be expanded into respective gripping and sealingengagement with a well conduit wall.

The well tool is shown as comprising a central mandrel 11 having a blindbore 12 and side ports 13 which can be opened and closed by a valvesleeve 14. A connector head 15 on the upper end of the mandrel 11 has aslot system 16 to provide a means for releasably connecting the mandrelto a running-in string of drill pipe or tubing (not shown). The mandrel11 is rotatively coupled to a compression sleeve member 18 by an annularshoulder 19 which engages within a recess 20 in the sleeve member. Anelastomeric packing element 22 is mounted around the sleeve member 18with its upper end engaging an annular abutment 23 on the sleeve member.A lower annular abutment 24 is slidable on the sleeve member 18 andengages the lower end of the packing element. Thus the packing element22 may be compressed and expanded in response to movement of theabutmcnts 23 and 24 relatively toward each other. A suitable seal ring21 can be provided for preventing fluid leakage between the sleevemember 18 and the mandrel 11.

The lower abutment 24 may be supported by a sleeve 25 which is connectedto an expander cone 26 having downward and inwardly inclined outersurfaces 27. The expander cone 26 can be coupled against rotationrelative to the compression sleeve 18 by coengaging splines 28 or thelike. Coengageable shoulders 29 and 30 are provided to limit downwardmovement of the expander cone 26 relative to the compression sleeve 18.

A tubular cage member 32 is movably mounted on the lower end portion ofthe mandrel 11 above an annular stop ring 33 which limits downwardmovement of the cage member relative to the mandrel. A plurality ofconventional drag blocks 34 are carried by the cage member 32 and areurged outwardly by coil springs 35 or the like. Moreover, a plurality ofslip elements 36 are pivotally connected to the upper end of the cagemember 32 by reins 37, the slip members having wickers or teeth 38 ontheir outer faces as well as inner inclined surfaces 39 which arecompanion in shape to the expander cone surfaces 27. Thus the slipelements 36 can be shifted outwardly into gripping engagement with awell conduit wall by downward movement of the expander cone 26 relativeto the slip elements, and a conventional dove-tail tongue and grooveconnection 40 can be provided to effect inward retraction of the slipelements upon upward movement of the expander cone 26 relative to thecage member 32.

A clutch nut assembly 42 in accordance with the present invention isprovided to enable selective control over relative movement between themandrel 11 and the cage member 32. With particular reference to thesomewhat enlarged drawing FIGURES 2 and 3, the clutch nut assembly 42comprises an annular member 43 which is radially cut into a plurality ofsegments 44, for example, four. The nut member 43 is received within anannular recess 45 which is somewhat enlarged relative to the nut memberto accommodate lateral expansion and contraction of the segments 44.Upper and lower resilient members such as band springs 46 and 47 arereceived within respective grooves in the segments and encompass the nutmember 43. Thus the segments 44 can expand and contract laterally whilebeing constantly urged inwardly by the band springs 46 and 47. Relativerotation between the various segments 44 and the cage member 32 can beprevented by lugs 48 projecting inwardly into vertically extending slots49 formed in the periphery of each segment. The upper and lower walls ofthe recess 45 can be formed as oppositely inclined surfaces 50 and 51,which are shaped for engagement with upper and lower inclined endsurfaces 52 and 53 on the respective nut segments 44.

Each segment 44 has spaced upper and lower threaded sections with teeth55 and 56 of the buttress type having transverse surfaces facingrespectively downwardly and upwardly. The upper threads 55 are of arelatively finethread construction and are formed on a left-hand helix,while the lower threads 56 are relatively coarse and are formed on aright-hand helix. The lower threads 56 are formed to have a through boresize which is at least as great as the root diameter of the upperthreads 55.

The mandrel 11 is formed to have spaced upper and lower threadedportions 57 and 58, the upper threads 59 being companion in shape andsize to the upper segment threads 55 and the lower threads 60 beingcompanion in shape and size to the lower segment threads 56. Thus theupper threads 59 have transverse surfaces facing upwardly and areleft-hand threads, while the lower threads 60 have transverse surfacesfacing downwardly and are right-hand threads. The lower mandrel threads60 can be formed over a vertical extent approximately equal to thevertical extent of the lower segment threads 56, while the upper mandrelthreads 59 can be formed over a significantly greater peripheral extentof the mandrel 11. Thus the lower mandrel and segment threads 60 and 56may have a single relative point of engagement, while the upper mandreland segment threads 59 and 55 can be engaged over a relatively widerange of relative positions of the mandrel 11 and the cage member 32.Due to the formation of the various threads, the lower mandrel threads60 can be screwed downwardly and disengaged from the lower segmentthreads 56 in response to righthand rotation of the mandrel; continueddownward mandrel movement without rotation will cause the upper mandrelthreads 59 to ratchet through and engage the upper segment threads 55.In like manner, right-hand rotation of the mandrel 11 can cause theupper mandrel threads 59 to screw upwardly out of engagement with theupper segment threads 55. Continued upward mandrel movement withoutrotation will cause the lower mandrel threads 60 to ratchet back intoengagement with the lower segment threads 56.

OPERATION The present invention can be assembled as shown in thedrawings and lowered into a well conduit with the mandrel 11 coupled toa running-in string of tubing or drill pipe. The drag blocks 34frictionally engage the inner conduit wall to yieldably resist movementin a conventional manner. The mandrel 11 is extended relative to theslip cage 32, and the slips 36 and packing element 22 are in normallyretracted positions. The lower mandrel threads 60 engage the lowerthreads 56 of the nut segment 44 to prevent upward movement of the cagemember 32 relative to the mandrel 11, thus preventing upward movement ofthe slips 36 toward the expander cone 26 during downward shifting of thetool to setting depth. Inasmuch as the slips 36 cannot move toward theexpander cone 26, or vice versa, the slips cannot be inadvertentlyshifted into gripping engagement with the well conduit during lowering.

When it is desired to set the tool, of course the tool is halted, andthen the mandrel 11 is rotated by the running-in string to the right. Ifdesired, such right-hand rotation can be accompanied with a small amountof further lowering movement of the mandrel 11. The drag blocks 34 willprevent rotation of the cage member 32, and since the nut segments 44cannot rotate relative to the cage member due to engagement of the lugs48 within the slots 49, it will be appreciated that the lower mandrelthreads 60 will be screwed downwardly and out of engagement with thelower segment threads 56, thereby enabling downward movement of themandrel 11 relative to the cage member 32 without further rotation. Thecoarse construction of the threads 56 and 60 enables release in responseto only a very few turns of the runningin string. Such downward movementwill effect expansion of the slips 36 into gripping and supportingengagement with the well conduit, whereupon the weight of the running-instring may be imposed upon the mandrel 11 to compress and expand thepacking element 22. As the mandrel 11 is thus moved downwardly, therelatively fine upper mandrel threads 59 will ratchet through thecompanion upper segment threads 55 due to the camming action of thelower thread faces against corresponding faces on the segment threads,and to the ability of the segments to expand and contract laterallywhile being constanly urged inwardly by the band springs 46 and 47.Inasmuch as the bore through the lower segment threads 56 is at least aslarge as the root diameter of the upper mandrel threads 55, the uppermandrel threads can readily pass downwardly through the lower segmentthreads 56 without interference. Due to the upwardly and downwardlyfacing form of the respective mandrel and segment threads 59 and 55, itwill be apparent that the mandrel 11 will become trapped in thelowermost position to which it is moved relative to the cage member 32to trap compression loading in the packing element 22 and thereby lockthe tool in set condition. The fine-thread construction of the threads55 and 59 enables efiicient trapping of the compression loading in thepacking element 22 because the relatively small pitch of these threadsensures that all or practically all of the downward movement of themandrel to be retained by the clutch nut assembly 42. The upper mandrelthreads 59 can have a considerable vertical extent to accommodate a widerange of relative movement requirements for expanding the slips 26 andthe packing element 22.

With the tool locked in set condition, it will remain until it isdesired to remove it from the well. Removal of the tool may beaccomplished by rotating the mandrel 11, again to the right, relative tothe cage member 32. By virtue of the left-hand formation of the threads59 and 55, right-hand rotation of the mandrel will result in upwardfeeding of the mandrel relative to the cage member. Such right-handrotation may be accompanied by upward strain on the running-in string ifdesired. Upward movement of the mandrel 11 relative to the cage member32 will effect release of compressive force on the packing element 22,which will inherently retract, and eventual upward movement of theexpander cone 26 relative to the slips 26, causing the latter to shiftinwardly to retracted positions. Upward movement of the mandrel 11 canbe continued until the lower end surface of the cage member 32 shouldersagainst the gauge ring stop 33, at which point the lower mandrel threads60 will have ratcheted back into engagement with the lower segmentthreads 56. Accordingly, the cage member 32 is again secured againstlongitudinal movement relative to the mandrel 11, and the tool can beretrieved from the well or moved to another setting position.

Since only one clutch nut assembly 42 is utilized in accordance with thepresent invention, the overall length of the cage member 32 can berelatively short to increase the compactness of the tool and reducemanufacturing costs. Since the respective upper and lower segmentthreads 55 and 56 extend continuously about respective inner peripheralportions of each segment 44, there is substantially full circleengagement with the mandrel threads 59 and 60 to evenly distribute theloading therebetween. Finally, since the lower segment threads 56 aresized to pass the upper mandrel threads 59 without interference, theupper mandrel and segment threads 59 and 55 can be expeditiously engagedwithout undue lateral ratcheting action of the segments 44 so as toobviate the problems of cocking and canting and failure to properlyengage. Since certain changes or modifications may be made in thepresent invention without departing from the inventive conceptsinvolved, it is the aim of the appended claims to cover all such changesand modifications falling within the true spirit and scope of thepresent invention.

I claim:

1. In a well packer apparatus having settable packing and adapted to bereleasably locked in both the running or retrieving and the setconditions in a well bore, the improvement comprising: a body memberadapted for connection to a running-in string; a clutch nut assemblysurrounding said body member and having a plurality of transverselyaligned arcuate segments which together form a generally cylindricalstructure, each segment having spaced upper and lower internal threadsformed respectively in the left hand and the right hand directions;resilient means urging said segments together as a cylinder butpermitting radial expansion thereof; and spaced upper and lowercompanion external threads on said body member engageable withrespective threads on said segments by longitudinal movement withoutrotation and releasable from respective threads on said segments byrotation of said body member relative to said clutch nut assembly in onerotational direction, said lower threads on said segments and said bodymember being relatively coarse threads and asid upper threads on asidsegments and said body member being relatively fine threads, said lowerthreads on said segments defining a through bore having a diameter whichis at least as great as the root diameter of said upper threads.

2. In a well packer apparatus having settable packing and adapted to bereleasably locked in both the running or retrieving and the setconditions in a Well bore, the improvement comprising: a clutch nutassembly having a plurality of transversely aligned arcuate segmentswhich together form a generally cylindrical structure, each segmenthaving spaced upper and lower internal threads formed respectively inthe left and the right hand directions, said lower threads beingrelatively coarse threads and said upper threads being relatively finethreads, said clutch nut assembly including resilient means for urgingsaid segments together as a cylinder but permitting radial expansionthereof.

3. The apparatus of claim 2 wherein said upper and lower threads areformed on difierent diameter, said lower threads defining a through borehaving a diameter which is at least as great as the root diameter ofsaid upper threads.

References Cited UNITED STATES PATENTS 2,831,542 4/1958 Lynes et a1.166-237 X 2,893,492 7/1959 Brown 166-119 3,279,542 10/1966 Brown 166-1393,288,219 11/1966 Young et a1. 166-134 X 3,311,173 3/1967 Henslee et al.166 15O 3,385,365 5/1968 Young 166-123 X 3,294,172 12/1966 Brown 166-139DAVID H. BROWN, Primary Examiner U.S. Cl. X.R. 166-123, 139, 182

